Set Campaign Business Logo

Replaces the BUSINESS LOGO shown in a campaign's ads (the small square logo next to the business name).

A campaign accepts only ONE advertiser business logo, so linking a new one with manage_extension_assets fails with a resource limit while the old one is still attached, and unlinking first leaves the ads without a logo in between. This tool does the swap in one atomic request: it links the new logo as BUSINESS_LOGO and unlinks the old advertiser logo together. The new logo must already be in the account's asset library as a SQUARE (1:1) image of at least 128x128 px (upload_image_asset with aspect='1:1' adds it); its asset id goes here.

With `asset_id` empty it READS which logo the campaign shows today without changing anything. Logos Google created AUTOMATICALLY from the website are listed separately and are not touched; they do not block the swap. confirm=false returns a dry run naming the old and the new logo; confirm=true applies it and reads the result back from Google. The link is per campaign; each campaign that shows the logo needs its own call.